The invention relates generally to medical imaging devices and more particularly to such devices which use energy conversion devices to obtain an electrical signal in response to gamma radiation.
Medical imaging is accomplished by inducing a patient with a radiopharmaceutical substance by means of injection, swallowing, breathing, or other appropriate method. The radioactive isotope of the radiopharmaceutical migrates to the target area to be examined and results in gamma radiation from it. The radiation can be sensed and used to generate an image of some features of the target area to provide information for approprate treatment. The image is presently generated by one of various types of computer assisted tomography (CAT) systems or the like.
Sensing of radiopharmaceuticals in animals and humans is accomplished today in essentially two ways. First, large gamma cameras containing collimators and two dimensional position-sensitive radiation detectors with fields of view of 12xe2x80x3 in diameter or more and detector heads weighing hundreds of pounds are used to make two-dimensional organ images, sometimes in a stationary mode and sometimes in a scanning mode. They are also used to make three dimensional organ images by taking several views of the same organ from different angles and using image reconstruction techniques to compute the concentration of radiopharmaceutical in three dimensions in a procedure called single photon emission tomography, or xe2x80x9cSPECTxe2x80x9d. The objective is to image the uptake of radiopharmaceuticals in the organs or systems of interest.
In the second method a single radiation detector without imaging capability is used to locate radioactive regions by manually scanning the single detector and its collimator over the region of interest to locate xe2x80x9chot spotsxe2x80x9d, for example indicating the presence of radiopharmaceutical tailored to be taken up by cancerous tissue. This technique is an aid in location of tissues of specific interest for which the radiopharmaceutcial is tailored, for example cancerous tissues, and specifically in some cases to aid surgeons in locating cancerous tissue and in determining if all the malignant tissue has been removed. Movement of the sensing radiation detector is essential to the technique. A 2-D (two-dimensional) or 3-D (three dimensional) image from a gamma camera might have advantages in surgery compared to the slow, cumbersome, risky method of scanning the single channel detector by moving it and it""s inherently small field of view manually to locate radioactive tissue, but the massive size of the gamma camera""s detector head precludes practical use in the crowded surgical theater. It""s size similarly precludes practical sterilization. Accordingly, there is a need for a smaller, more portable apparatus for obtaining a medical image from the gamma radiation.
In accordance with the present invention there is provided a novel compact medical nuclear imaging device for generating a medical image from gamma radiation. It can be made small enough to be available for use in the course of surgery for making available in real time important information about the target surgery region.